Tarunda lowers enemy attack power for three turns and Sukukaja improves ally hit and evasion rate for three turns.

lol they're too distracted by her bikini to cast the spells correctly

^
I more think that Akihiko is casting tarunda on his junk, f you catch my drift.

Yeah, they're casting it on themselves:

Akihiko is casting Tarunda to get his Mara down. Junpei doesn't know Sukukaja on his own (his in-game support skill is actually Rakukaja), but maybe it's to ensure that he's agile enough not to get too close to Hamuko.

They're liable to push her down if they don't buff/debuff themselves.

Hahaha, All-Out Attack.